Color image processing systems often include an input device (e.g., a scanner, copy machine, etc), an image manipulation device (e.g., a workstation) and one or more output devices (e.g., monitors, rendering devices, color print presses, etc.). Within such systems, consistency of color reproduction across system components is desirable. It is also desirable to attain similar consistency of color reproduction when image files are transferred between different color image processing systems.
Gamut mapping is necessary because different imaging devices have different color capabilities, describe color characteristics in varying terms, and operate among variable color spaces. Most prior art mapping approaches are capable of converting images from one color gamut to another, but do not map a representational gamut (e.g., printer or CRT) with a target gamut (e.g., camera, scanner, monitor or RGB gamut). For example, images in a source space rendered utilizing a colorimetric mapping do not preserve saturation information. For example, a full saturation green, as displayed on a monitor, may appear as a washed-out green on a rendering device.
Conversely, graphic edge colors are preserved utilizing a device mapping that merely preserves hue; however, such device mapping can over-saturate the colors such as skin tones associated with the image. Additionally, such prior art approaches typically employ different individual transformation tables for images and graphics. Multiple transformation tables for different object types can destroy the relationship between the graphic data and the images. For example, maps are often displayed as images, but map keys or inserts on a map are often displayed as graphics. If the transformation table for a map's key does not match the transformation table for the map itself, it is problematic for displaying required colors for that rendered map. For example, if a specific forest green is required to represent a forest on a map, the rendered map and any keys/inserts with differing transformation tables may result in a washed-out green when rendered. Furthermore, a gamut function obtained by morphing the colorimetric mapping and device mapping cannot be easily inverted and may create unintended transitions with respect to the image.
Based on the foregoing, it is believed that a need exists for an improved system and method for mapping color gamuts based on one-one and mapping functions in order to create an invertible transform. A need also exists for an improved method for partitioning color gamuts to preserve hue angle, saturation, and lightness, as described in greater detail herein.